Problem: What's the first wrong statement in the proof below that $ \triangle BDE \cong \triangle BCE$ $ \; ?$ $ \overline{BC} $ is parallel to $ \overline{DF} $. This diagram is not drawn to scale. A B C D E F Givens $ \overline{EF} \cong \overline{BE}$ $, \ $ $ \angle CEF \cong \angle BED$ $, \ $ $ \angle ECF \cong \angle BDE$ $, \ $ $ \overline{AC} \cong \overline{DE}$ $, \ $ $ \angle ACB \cong \angle BDE$ $, \ $ and $\ $ $ \angle ABC \cong \angle DBE$ Proof $ \triangle BDE \cong \triangle FCE$ because AAS $ \overline{DE} \cong \overline{CE}$ because corresponding parts of congruent triangles are congruent $ \overline{CE} \cong \overline{AF}$ because corresponding parts of congruent triangles are congruent $ \triangle BDE \cong \triangle BCA$ because AAS $ \angle BAC \cong \angle BED$ because corresponding parts of congruent triangles are congruent $ \triangle BDE \cong \triangle BCE$ because SSS
Solution: Try going through the proof yourself: write down the givens, and then see if they justify the next step for the reason given. Then do the same thing for the next step, and the next, until you run into something that you can't justify, or you finish the proof. $ \overline{AF} \cong \overline{CE}$ is the first wrong statement.